The invention relates to a closing body, in particular a valve cone for a constant pressure valve, for controlling fluidic pressure medium, having a sealing section and a guide section which allow an overflow of pressure medium between the two sides of the closing body.
Such a closing body formed as a valve cone has been disclosed by DE 199 07 732 A1. The valve cone is mounted in an axially displaceable manner in a bore of a directly actuated hydraulic proportional pressure relief valve. It has a conically formed sealing section and a guide section. The tip of the sealing section interacts with a seating bore. Formed between the outlet opening of the seating bore and the conically formed sealing section is a choke gap which controls the pressure medium flow and the size of which depends on the position of the valve cone. The guide section has two subsections which guide the valve cone and between which a further section of smaller diameter is arranged. The cylindrical subsections serving for the guidance are provided with a plurality of flats which are distributed uniformly over the circumference and which allow an overflow of pressure medium between the two sides of the valve cone. The flats permit a pressure balance between the two sides of the valve cone, so that the same pressure acts on the valve cone from both sides. The starting material or the production of a valve cone having overflow flats in subsections of the guide section is either round material which is provided with flats during the machining or material of square cross section whose edges are rounded during the machining in such a way that the outside diameter of the subsections serving for the guidance corresponds to the inside diameter of the valve cone bore. Both production variants are therefore very costly. When round material is used, the valve cones, on account of the overflow flats, must be set up for individual grinding operations, either in order to subsequently provide the sealing and guide sections, ground in a centerless manner in a preceding operation, with flats in the region of the guide section, or in order to grind the guide section of the valve cone already provided with flats and the sealing section in two separate operations, since simultaneous centerless grinding of guide and sealing sections is not possible on account of the flats. When material of square cross section is used, a turning operation with interrupted cut is necessary in order to produce the rotationally symmetrical regions. In order to produce the valve cone at the sealing section and at the guide section with small coaxiality tolerance, the two sections have to be ground between centers. However, no centering bore for grinding between centers is admissible directly at the contact surface between the valve cone and a plunger interacting with the latter. A peg-shaped extension having a centering bore therefore has to be provided on this side and is to be shortened by the length of the centering bore after the grinding.
The object of the invention is to provide a closing body of the type mentioned at the beginning which can be produced cost-effectively.